This presentation is related to types mechanism of neuromuscular blockers.

1. NeuromuscularBlockers
Name:MuhammadHaiderAli
RollNo:43

2. Definition:
 Alsoknownasskeletalmusclerelaxants.
 Thesearethoseagentsindrugswhichareusedtoblockthecholinergic
transmissionbetweenmotornerveendingandnicotinicreceptoronthe
neuromuscularendplateofskeletalmuscle.
 Neuromuscularjunction:junctionbetweenneuronandmusclesinwhich
Neurotransmittersreleasefromneuronandbindwithreceptorspresentonmuscles
andcausecontractionandmovement.

4. TypesofNeuromuscularBlockers:

5. Non-depolarizingblockers:
 Thesedrugsdoesnotdepolarizethemotorendplate.
 Thequaternaryammoniummusclerelaxantsbelongtothisclass.
 Quaternaryammoniummusclerelaxants arequaternaryammoniumsaltsusedasdrugsformuscle
relaxationmostcommonlyusedin anesthesia.Itisnecessarytopreventspontaneousmovementof
muscleduringsurgicaloperations.
 Whicharepoorlyabsorbedandrapidlyexcretedandcan'tcrossplacenta.
 Theyinhibitneuron transmissiontomusclebycompetitivelyblockingthebindingof
acetylcholine(Ach)toitsnicotinicreceptorsandblocktheionotropicactivityof theAchreceptors.

6. Non-depolarizingdrugs:
 Longacting:
i. Pancuronium
 Intermediateacting:
I. Atracurium
II. Vercuronium
III. Rocuronium
IV. Cisatracurium
 ShortActing:
I. Mivacurium

7. DepolarizingBlockers:
 AnexampleisSuccinylcholine.
 Themostcommonlyuseddepolarizingblockerissuccinylcholine(alsocalledsuxamethoniumor
SCh).Whenadministeredintravenously,succinylcholinerapidlybindstothenicotinicacetylcholine
receptorsonthemotorendplateofskeletalmuscles.Itcausesabrief initialdepolarization,which
leadstomusclefasciculationortwitches.
 However,succinylcholine'suniquecharacteristicisthatitismetabolizedmoreslowlythan
acetylcholine.

8. Succinylcholine:
 DoserequiredforTrachealintubationinadultsis 1.0-1.5mgkg.
 Thisdoseproducesprofoundblockwithin60sec.
 Butveryshortdurationofactionabout5-10minutesbecauseofPlasmacholinesterase,whichhasan
enormouscapacitytohydrolyzesuccinylcholine.

9. Name: M.Rabeet Ahmed
Roll No:46

10. Mechanism ofAction(Non-Depolarizing):
 Thecompetitiveblockerhaveaffinityforthenicotiniccholinergicreceptoratthemuscleend
plate,buthavenointrinsicactivity.
 Thetwoα-subunit carrytwoacetylcholine(Ach) bindingsitesinNicotinicreceptor.
 Mostofthecompetitiveblockersattractforthesamesite,butduetobulkynatureofcompetitive
blockersmoleculesdoesnotallowconformationalchangesinsubunitsforopeningofchannel.

11.  Acetylcholine (Ach) molecule released fro motor nerve ending
are not able to combine with the receptor of end plate
potential.
 There fore muscle fails to contract.

12. FigureofNon-Depolarizing blockers:

13. Mechanism ofAction(Depolarizing):
 Thedepolarizingagentsuchassuccinylcholineactbydifferentmechanism.
 Theirinitialcationistodepolarizethemembranebyopeningchannelsinthesame
mannerasacetylcholine.
 Butthedepolarizingisforlongertimebecauseacetylcholine(ach)isdestroyedby
cholinesterase.

14.  Longer lasting depolarization make receptor incapable for
further signaling.
 Therefore muscle fails to contract. These drugs produce rapid
complete paralysis and the recovery is spontaneous.

15. FigureofDepolarizingblockers:

16. Uses:
 Acutemusclespasms:Themephenesin-like andBZDmusclerelaxants,combinedwith
analgesics.
 Torticollis(tiltedandtwistedneck),lumbago (paininthemuscleandjointsofthelowerback),
backache,neuralgias(paincausedbydamagednerves)
 Anxietyandtension:Diazepamgroup
 Spasticneurologicaldiseases:Theseconditionsarebenefitedbybaclofen,diazepam,tizanidine
anddantrolene.
 Tetanus:Diazepam,methocarbamol
 Electroconvulsivetherapy:Diazepam
 Orthopedicmanipulations:Diazepam,methocarbamol